One idea could be a crossover where Merlin's magic system interacts with the magic of the Harry Potter world. Maybe the Reaper has some special role in uniting the two magical realms. For example, it could be a powerful entity that both Merlin and the wizards in Harry Potter's world need to face together, leading to a lot of new spells and magical discoveries.
One idea could be that Merlin uses his magic to help Harry Potter in his fight against Voldemort. Maybe Merlin's ancient magic knowledge gives Harry an edge in finding Horcruxes. Another could be that the characters from the two universes meet at Hogwarts, like Merlin being a special guest lecturer, sharing his experiences of magic in a different era.
Well, perhaps a plot where the Eyes of Merlin are the key to unlocking an ancient prophecy that has been misinterpreted all along. This could lead to a race between the good and bad forces in the Harry Potter universe to either use it for good or evil. Also, it could be that a character who has the Eyes of Merlin has to face a series of trials to fully understand and control their power, and these trials are set up by an old wizard who once possessed the Eyes.
Another interesting concept is a crossover where the Hogwarts students visit the reaper realm. Harry, Hermione, and Ron could be intrigued by the reaper's way of life and the way they handle souls. The Undertaker could be their guide, showing them the secrets of the afterlife according to the reaper lore. This could lead to new spells or magic being discovered as they learn from the reapers.
One idea could be that Merlin is reborn as a student at Hogwarts. He could use his ancient magic knowledge to solve some of the mysteries that even Dumbledore has trouble with. For example, he might be the key to understanding the true nature of the Chamber of Secrets in a way that no one has thought of before.
A possible plot is that Merlin disguises himself as an ordinary wizard at Hogwarts and secretly mentors Harry. He could introduce Harry to magical creatures that have long been forgotten in the modern wizarding world but hold great power. He also might help Harry unlock some latent magical abilities within him that are related to Merlin's own magic, like the ability to communicate with magical spirits that can offer valuable advice in the battle against Voldemort.
One idea could be that Merlin somehow gets transported to the Harry Potter universe. He could use his magic, which is different from the wizarding magic in Harry Potter, to solve some of the mysteries or problems there. Maybe he teams up with Harry and helps him defeat Voldemort in a unique way, like using his ancient magic knowledge.
One interesting idea could be how the magic from Merlin's time influences the wizarding world in Harry Potter. Maybe there are ancient spells or magical artifacts passed down through Merlin's inheritance that play a crucial role in the fight against Voldemort.
One idea could be a crossover where Merlin uses his magic to help Harry in a difficult situation at Hogwarts, like when he's facing a powerful dark wizard. Merlin's ancient magic might be different from what's taught at Hogwarts and could offer a new perspective on solving problems.
Harry Potter himself could be one of the main characters. He might be the one to discover the connection between his world and Merlin's through the presence of the Reaper. His natural curiosity and courage would make him a key figure in exploring this new mystery.
Well, perhaps Draco, in the role of Merlin, has a special connection to the magical creatures that he uses to help Harry. Harry, as Arthur, is trying to unite the different factions of the wizarding world. Draco's knowledge of magic, similar to Merlin's, allows him to create magical artifacts or spells that assist Harry in his quest for unity. And there could be a love story involved too, like Guinevere and Arthur, but in the context of the wizarding world with some other character and Harry.